Ronaldo, now 41, returned to Manchester United back in back in 2021, scoring 27 goals in his 54 games across all competitions under Ten Hag.
Despite his solid scoring record, the legendary forward was largely criticised for his inability to press and struggled to play as part of the team rather than an individual.
The relationship between Ronaldo and Ten Hag completely broke down during their time together, and the former went as far as saying he had no respect for his former boss during an interview with Piers Morgan.
Now, Ten Hag has offered his perspective, saying in a recent interview: "The players wanted to work for him and looked up to him because he is one of the greats of all time.
"But over the last seven or eight years, he simply can no longer deliver.
"From Juventus, it's simply over."
Ten Hag then claimed that Ronaldo was unwilling to put in the work to be fit enough to lead the line for a top Premier League side.
"When I started at Man United, I explained to him how we were going to play and what his role in that would be,” he added.
"But ultimately, you have to deliver. But he could no longer bring himself to push through the pain to give everything every single day and to train at his maximum.
"And if you are not fit to play in the Premier League, you have no chance.”
He was then asked about the image of Ronaldo having always gone the extra mile.
"Well, that was the image. But he could no longer bring himself to do that.
"You show him what is required, and he knows it too, and you come to him with arguments that hold up."
Regarding Ronaldo’s response to Ten Hag’s demands, the Dutchman added: "No, he doesn't say that because the evidence was so clear. So he had to make a choice.
"At that moment, I have to make a decision that is in the best interests of the club and of the team.
"I know that I did everything I could to persuade him (to be Premier League fit), but the choice is with the individual as to whether he wants to make that investment.
"And if you don't want to, I have to make different choices in the interest of the team, and that's what we saw."
On the added noise around Ronaldo, he said: "No one is bigger than a club or a country not even Messi or Ronaldo.
"In the end, the team always comes first."